Radiotelegraphy.



" L. F. FULLER.

RADIOTELEGRA PHY. APPLICATION FILED MAR.2I. 1955.

1,300,156. I Patented Apr. 8,1919

(NVENTQR. .4. F. FULLER ATTORNEYS.

WITNESSES:

UNITED STATES PATENT OFFICE.

LEONARD F. FULLER, OF SAN FRANCISCO, CALIFORNIA, ASSIGN OR TO FEDERAL TELEGRAPH COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF,

CALIFORNIA.-

RADIoTELEeaArHY.

AppIication filed March 27, 1916. Serial No 86,934.

T 0 all whom it mayconcem:

. Be it known that I, LEONARD F. FULLER, a citizen of the United States, and a resident of the city and county of San Francisco and State of California, have invented certain .new and useful Improvements in Radiotelcgraphy, of which the following is a specification. I The invention relates to 'a transmission system for radiotelegraphy and particularly to a mean for producing signals.

An object of the invention is to provide a signaling apparatus or key, capable of handling large currents.

Another object of the invention is to provide a key capable of handling large currents which may be operated at high speed.

The invention possesses other advantageous features, which, with the foregoing, will be set forth at length in the following description where I shall outline in full that form of the invention which I have selected for illustration in the drawingaccompanying and forming part of the present specification. The invention may be embodied 1n other forms and I do not limit myself to the form shown in the drawing.

The apparatus of this inventionis par.- ticularly useful in a. transmission.system employing continuous oscillations, and'particularly a system employing an'arcas the source of continuous oscillations. In such systems, signals are produced by making a small change in the length of the radiated wave and this is usually accomplished by varying the inductance of the oscillatory circuit, preferably by short-circuiting a portion of the inductance. In high power transmitting stations, the currents which must be handled by the short circuiting apparatus are large and diiiiculty has heretofore been experienced in opening and closing the cirzcuit.

In accordance with my invention, I provide a multiple contact key, so'arranged that each contact carries only a portion of the current, regardless of whether all of the contacts are, closed or opened at the same time or not.

In the drawing I have shown diagrammatically a radiotelegraph transmission system embodying the apparatus of my invention.

The system comprises a source of continuous oscillations 3 preferably an are, which is supplied with current through the con-- ductors 45 from a source of direct current. Cne side of the oscillation source is grounded by the conductor 6 and the other side is connected to the antenna 7 through the variable inductance 8. Signaling is accomplished by varying the amount of inductance in circuit. Connected to the inductance at spaced points, preferably at that portion which lies adjacent the oscillation source, are a plurality of conductors 12 13-14. which are provided on their ends with con- Patented Apr. 8, 1919. I

tacts 15, 1617 and 18. Connected to the q inductance at points intermediate the points of connection of conductors 1213 and 13-44 are conductors 2122, which' are provided on their ends with contacts 25%26 and 27-28. The contacts 25262728 are respectively alined with contacts 15'-16 l718 and the contacts 25, 26, 27 and 28 are mounted on amovable element so that they may be readily moved into engagement with the other set of contacts. In the present instance the 'movable series of contacts are mounted on and insulated from a bar 29 which is attached to the core of the solenoid 31. The current in the solenoid which produces the movement of the core may be con-- trolled by an ordinary telegraph sending key operating through a suit-able relay, or directly.

The total inductance short-circuited by the multiplecontactkey is theinductance necessary to produce the desired change in wavelength, and by breaking this inductance'into'a plurality of sections, and'shortcircuiting each section independently, only a portion of the energy impressed on the key is handled by each contact. The energy nected to the inductance at points interme diate said first named points and means for moving one of said groups of contacts to connected to the inductance at spaced points, a second plurality of contacts connected'to the inductance at a plurality of points intermediatesaid first named points and means for moving one group of contacts to bring the contacts therein into engagement with the contacts in the other group, the contacts being so arranged that a contact in the first group engages the contact in the second group which is connected to the inductance at a point adjacent the point of connection .oof the contact of the first group with the inductance.

3. In a radiotelegraph transmission system, an inductance, a plurality of contacts connected to said inductance at spaced points, a second plurality of contacts connected to the inductance at intermediate points, abar on which one of said groups of contacts is arranged and means for-moving said ,bar to bring the groups of contacts into engagement.

4. In. a radiotelegraph transmission system, an inductance, a key comprising a fixed member having a plurality of contacts connected to the inductance at spaced points and a movable member having a plurality of contacts connected to the inductance at .spaced points intermediate the former spacedipoints and means for opening and closing the circuits between the adjacent contacts whereby each contact carries only a portion of the energy impressed 0n the key regardless Of the sequence of opening and closing of the individual circuits.

In testimonywhereof, I have hereunto set my hand at San Francisco, California, this 21st day of March 1916.

. LEONARD F. FULLER.

In presence of H. G. Pnos'r. 

